The purpose of this study is to assess the safety, tolerability and pharmacokinetics of ABT-122 in subjects with Rheumatoid Arthritis.

This is a phase 1, randomized, double-blind, placebo-controlled, multiple ascending dose study. Twenty-four subjects with Rheumatoid Arthritis will be selected to participate. Subjects will be randomized to receive either ABT-122 or placebo. ABT-122 or placebo will be administered as subcutaneous (under the skin) injections in three dosing groups.

Inclusion Criteria:

• Diagnosis of Rheumatoid Arthritis (RA) > 3 months.
• On methotrexate (MTX) therapy => 3 months and on a stable dose for at least 4 weeks.
• Except for MTX, must have discontinued all disease-modifying antirheumatic drugs (DMARDs) for at least 3 months or 5 half-lives, whichever is longer.
• Body Mass Index (BMI) is 19 to 38, inclusive.
• Other than RA, subjects should be in good general health.

Exclusion Criteria:

• Evidence of anti-ABT-122 antibody on a serum sample taken at Screening.
• History of significant allergic reaction; or history of anaphylactic reaction to any agent; or history of major reaction to any IgG containing product.
• History of persistent chronic or active infection(s) requiring hospitalization or treatment with intravenous or oral anti-microbials/antibiotics within the past 30 days.
• History or evidence of active tuberculosis (TB) or the subject has evidence of risk factor for latent TB.
• Subject has any medical condition or illness other than RA that is not well controlled with treatment.